A basic and applied remote sensing research project (GRAPEX) for actual evapotranspiration monitoring to improve vineyard water management

Authors: Kustas, William - Bill; Knipper, Kyle; ALSINA, M. - E & J Gallo Winery; BAMBACH, N. - University Of California, Davis; McElrone, Andrew; Prueger, John; Alfieri, Joseph; BHATTARAI, N. - University Of Oklahoma; Anderson, Martha; TORRES, A. - Utah State University; NIETO, H. - Institute Of Agricultural Sciences; Gao, Feng; HIPPS, L.E. - Utah State University; McKee, Lynn; CASTRO, SEBASTIAN - University Of California, Davis; AGAM, NURIT - Ben Gurion University Of Negev; Crow, Wade; BURCHARD-LEVINE, VICENTE - Utah State University; JIN, YUFANG - University Of California, Davis; DOKOOZLIAN, NICK - E & J Gallo Winery

Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: The cultivation of wine grapes is worldwide with over 7 million hectares of vineyards distributed over 100 countries on six continents. California and other western states, as well as water-limited regions across the globe, are facing serious water shortages due to drought and overdraft of major aquifers. Regulated deficit irrigation by monitoring actual water use or evapotranspiration (ETa) is key to improve water use efficiency, conserve water, and lead to sustainable production, while remaining economically viable. The GRAPEX (Grape Remote sensing Atmospheric Profile and Evapotranspiration eXperiment) project goal is to develop a remote sensing-based toolkit for monitoring vine ETa and vine water status to efficiently use and conserve water. We are combining earth observations from satellites with unmanned aerial vehicles (UAVs) imagery in energy balance modeling systems using spectral and thermal-based approaches. The GRAPEX project has yielded both theoretical and applied research results at scales from leaf to canopy, and vineyard block to regional scales. Remote sensing from proximal, aerial, and satellite platforms with different spectral bands to detect vine stress conditions for these vineyard landscapes has been evaluated by GRAPEX researchers. There have also been models developed to estimate vineyard water balance for a more complete description of plant available water for irrigation scheduling. The research findings indicate potential for operational application of remote sensing information on vine leaf biomass, ETa, and vegetation indices for significant water savings through improved vineyard management and irrigation scheduling.

Technical Abstract: Wine grapes are grown world-wide and many in water limited regions. The impacts of climate change causing more frequent and severe droughts and heat waves has made it very challenging for sustainable production and to remain economically viable. A key goal of the GRAPEX (Grape Remote sensing Atmospheric Profile and Evapotranspiration eXperiment) project is developing remote sensing-based methods for monitoring actual vine water use (Evapotranspiration, ET) and vine water status to efficiently use and conserve water though improved deficit irrigation practices. To properly develop these methods for vineyards which typically have significant interrow spacing and a managed canopy architecture leading to strongly clumped vegetation with non-uniform vertical distribution of biomass, both basic and applied research is required involving the collection of multidisciplinary data sets. These included leaf-scale gas exchange, water potential and hyperspectral measurements, micrometeorological measurements of energy exchange above and below the vine canopy and in the interrow, biomass and leaf area measurements and soil moisture profile measurements together with tower-based, aircraft and satellite remote sensing data. An overview of the key findings from GRAPEX will be presented from both basic research on understanding soil-vine-atmosphere turbulent exchange processes and applied research efforts in the development of a remote sensing-based ET toolkit for improving irrigation scheduling and water conservation.